1. Field of the Invention
The present invention relates generally to the field of snow plows. More specifically, the present invention discloses a snow plow assembly in which a chain sliding in an arcuate guide is used to variably adjust the yaw angle of the blade, and which further has a spring/lever mechanism to enable the lower edge of the blade to roll upward and rearward if the blade strikes an obstruction.
2. Statement of the Problem
The present invention addresses a number of shortcomings heretofore found in snow plows designed for attachment to cars or other types of light vehicles. One problem is the substantial weight of the snow plow which usually dictates the need for some type of hydraulic or electrical system to regulate the angle of the blade. Another problem is the need to provide some means of minimizing damage to the blade if it strikes a curb or some other type of obstruction. In the past, this has sometimes been accomplished by including a deformable link or pin in the frame that is designed to yield if a predetermined force is exceeded. Another approach is to include an hydraulic cylinder that provides a degree of give and resilience in the support frame for the snow plow blade.
A number of snow plows have been invented in the past with various means to adjust the angle of the blade and to prevent damage in the event the blade strikes an obstruction, including the following:
______________________________________ Inventor Patent No. Issue Date ______________________________________ Sodemann 4,924,610 May 15, 1990 Slocum 4,821,436 Apr. 18, 1989 Morrell 4,813,164 Mar. 21, 1989 Rath 4,254,564 Mar. 10, 1981 Rust 2,614,344 Oct. 21, 1952 Abbe 1,709,244 Apr. 16, 1929 ______________________________________
Sodemann discloses a snow plow attachment in which the blade is vertically suspended by a cable 7.
Slocum discloses a plow system in which the angle of the blade about a vertical axis (i.e., yaw) is controlled by two sets of cables 68A and 68B through a winch 66 and pulley arrangement 67A, 69A, 67B, and 69B.
Morrell discloses an apparatus for mounting a snow plow 12 to the bucket 14 of a conventional frontend loader. The chains 34a and 34b extending from the snow plow frame 32 to the grab hooks 52 on the top edge of the bucket for raising and lowering the blade.
Rath discloses a reversible snow plow attachment in which a cable 14 is used to suspend the snow plow blade from an arm 13. Elevation of the blade is controlled by a hydraulic cylinder 12 that can raise or lower the arm 13. The angle of the blade with respect to its vertical pivotal axis is controlled to two hydraulic cylinders 26 and 27.
Rust discloses an arrangement in which a chain 61, 62 is used to adjustably control the elevation of a blade mounted to the front of a motor vehicle.
Abbe discloses another example of a device in which chains 8 and 12 are used to lift a snow plow blade attached to the front of a motor vehicle.
3. Solution to the Problem
None of the prior art references uncovered in the search show a snow plow assembly having the structural combination of the present invention. In particular, none of the prior art references teach or suggest the combination of a chain and arcuate track to control the yaw angle of the blade, together with a spring/lever mechanism to allow a small degree of forward roll of the blade to overcome obstructions.